<!DOCTYPE html>
<html>
	<head>
		<meta charset="UTF-8">
		<title>判断用户输入</title>
	</head>
	<body>
		<script type="text/javascript">
				var a=prompt("请输入:");
		if(Boolean(a)){
			alert("输入内容是："+a);
			
		}else{
			alert("您还未输入内容");
		}
		</script>
	</body>
</html>
